A novel and convenient self-drying system for bacterial preservation.

An effective microbial preservation technology for the long-term storage of viable prokaryotic cells is described. The method combines an almost instantaneous drying step with minimal stress to the cells during drying to maximize survival on rehydration. This is achieved by contact of a microlitre aliquot of a bacterial suspension with a novel, pre-dried activated charcoal cloth based matrix contained within a re-sealable system that can then be stored. The simple methodology completely circumvents the requirement for further drying or preparation. Using this method, a standard laboratory Escherichia coli strain was successfully revived following 390 days storage at 4, 20 and 30 degrees C. Data obtained yielded approximately 20%, 6% and 0.1% viable organisms at the aforementioned temperatures, respectively, following initial inoculations of 1.1 x 10(8)/microl cells. While these figures represent a significant viability loss, there is sufficient recovery of microorganisms required for maintaining culture collections.

Nonresponse error in mail surveys: top ten problems.

Conducting mail surveys can result in nonresponse error, which occurs when the potential participant is unwilling to participate or impossible to contact. Nonresponse can result in a reduction in precision of the study and may bias results. The purpose of this paper is to describe and make readers aware of a top ten list of mailed survey problems affecting the response rate encountered over time with different research projects, while utilizing the Dillman Total Design Method. Ten nonresponse error problems were identified, such as inserter machine gets sequence out of order, capitalization in databases, and mailing discarded by postal service. These ten mishaps can potentiate nonresponse errors, but there are ways to minimize their frequency. Suggestions offered stem from our own experiences during research projects. Our goal is to increase researchers' knowledge of nonresponse error problems and to offer solutions which can decrease nonresponse error in future projects.